PURPOSE: Provided is a novel organic photosensitizer which maximizes electric charge acceptance voltage and minimize electric charge discharge voltage, and which can generate high quality picture and keep the same picture quality after repeated cycles. The photosensitizer is used in electrophotography. CONSTITUTION: The organic photosensitizer comprises: (A) at least one electric charge transfer material containing fluorenone hydrazone from a combination of functional group selected from (a) at least two fluorenone alkyl sulfonyl phenyl hydrazone functional groups, (b) at least two fluorenone pyrrolyl hydrazone functional groups, (c) at least two fluorenone benzotriazolyl hydrazone functional groups, (d) at least two fluorenone sulfonyl hydrazone functional groups, (e) at least two fluorenone pyrazolyl hydrazone functional groups, (f) at least two fluorenone naphtyl hydrazone functional groups, (g) at least two fluorenone tetrazolyl hydrazone functional groups, (h) at least two fluorenone stilbenyl hydrazone functional groups and (i) at least two fluorenone (9H-fluorene-9-ylidene) benzyl hydrazone functional groups; (B) an electric charge generating compound; and (C) a support material for electric conductivity. The electric charge transfer material is represented by formula 1, wherein n is an integer of 2 to 6; R1 is hydrogen, alkyl, or aryl; R2 is the one selected among alkyl sulfonyl phenyl group or its derivatives; X is linear or branched bonding group of -(CH2)2-.